Knife sharpener



Jan. 24, 1950 A E. ANHEUSER 2,495,361

KNIFE SHARPENER Filed June 7, 1947 3 Sheets-Sfieet 1 Jan. 24, 1950 A E. AN'HEpsER 2,495,361

KNIFE SHARPENER 3 Sheets-Sheet 2 Filed June 7, 1947 Jan. 24, 1950 A E. ANHEUSER 2,495,361

KNIFE SHARPENER Filed June 7, 1947 3 Sheets-Sheet 5 Patented Jan. 24, 1950 KNIFE SHARPENER Alfred E. Anheuser, Milwaukee, Wis.

Application June 7, 1947, Serial No. 753,321

This invention relates to knife sharpeners and refers more particularly to an improved knife sharpener of the type having a file-like sharpening element.

While knife sharpeners of the type in which the sharpening element is formed from a file or a file-like cutting member are well known, an example being that shown in the patent to Bowles No. 1,451,526, such knife Sharpeners have heretofore had many disadvantages.

It is well known that hollow grinding of edged tools is more desirable than fiat grinding since it provides a keener cutting edge and one which remains sharplonger, butit was impossible to obtain a hollow grind with previous file type sharpeners because they employed sharpening elements having fiat grinding or sharpening surfaces.

It is an object of this invention, therefore, to provide a knife sharpener having a sharpening element of the file type which will produce a hollow ground blade edge on a knife or other edged tool drawn therethrough for sharpening.

Former file-element sharpeners had a further disadvantage in that the chips or shavings ground from the edge of the blade by the sharpening element tended to accumulate between the blade and the sharpening element, thus interfering with the progress of the sharpening operation, and tending to produce a ragged and unsatisfactory edge on the blade.

Hence it is an object of this invention to provide a file type knife sharpener which will provide superior sharpening by virtue of the fact that it precludes clogging of the file element by chips or shavings from the knife blade during sharpening thereof.

When a file element of the flat type is used in a knife sharpener, all of the serrations of the file lie in the same plane with respect to the surface of the blade to be ground and the path of the blade during sharpening thereof, and consequently each tooth of the file element tends to cut or shave the surface of the blade to an equal depth. Hence, if the first few teeth at the front of the file shave the blade edge surface to its maximum depth, the remaining teeth will take no 13 Claims. (Cl. 76-88) against the blade surface must be overcome in out therein so that the teeth at the front of the sharpening element will rapidly wear out while same depth, it is difiicult to begin drawing a knife through the sharpener because the grinding friction of all of the teeth on the sharpening element moving the blade through the first portion of the sharpening stroke.

Another object of this invention resides in the provision of a sharpener of the character described in which successive teeth or serrations along the length of the file element will shave or grind progressively deeper into the blade surface as the blade is advanced across them.

Another object of this invention resides in the provision of a sharpener of the character described which will produce a superior sharpening job by reason of the fact that the sharpening element is capable of grinding the edge surface of a blade to a depth beyond. the medial plane of the blade.

Still another object of this invention resides in the provision of a sharpener for knives and the like which will have an unusually long useful life by reason of the fact that it may be adjusted to compensate for wear to enable unused portions of the file element to be presented to the knife blade.

A further object of this invention resides in the provision of an improved sharpener of the character described in which a single sharpening stroke will grind both surfaces of a knife blade adjacent to its cutting edge.

With the above and other objects in view, which will appear as the description proceeds, this invention resides in the novel construction, combination and arrangement of parts substantially as hereinafter described and more particularly defined by the appended claims, it being understood that such changes in the precise embodiment of the herein-disclosed invention may be made as come within the scope of the claims.

Theaccompanying drawings illustrate several complete examples of the physical embodiment of the invention constructed according to the best modes so far devised for the practical application of the principles thereof, and in which:

Figure 1 is a perspective view of one embodiment of the knifesharpener of this invention;

Figure 2 is a rear elevational view of the sharpener shown in Figure 1;

Figure 3 is a side view of the sharpener shown in Figure 1, portions thereof being cut away;

Figure 4 is a top view of a modified embodiment of the sharpener of this invention;

bodiment of the sharpener of this invention, portions thereof being cut away;

Figure '7 is a top view of the Figure 6 embodiment;

Figure 8 is a perspective view of the sharpening element of the Figure 6 embodiment; and

Figure 9 is an elevational view on the order of Figure 6 but showing a slightly modified embodiment of the knife sharpener therein illustrated.

Referring now to the accompanying drawings and more particularly to Figures 1, 2, and 3, the numeral 5 designates one form of knife sharpener of this invention. The sharpening element 1 thereof is substantially cylindrical and is supported over a fiat base 5 from spaced standards 8 and 8 thereon at the front and rear of the base respectively and which receive the sharpening element endwise therebetween; the base providing means for securing the sharpener to the surface of a table or workbench.

The sharpening element 1 has numerous closely spaced cutting ridges or teeth 9 on its cylindrical surface which may either be threadlike or concentric if desired. All of the teeth, however, are undercut and have their cutting edges facing the standard 8 at the front of the base.

The file-like sharpening element 1 is provided with an axial mounting hole I and is supported at a convenient height above the base by a set screw ll passing through suitable holes in the standards and through the mounting hole 10 in the file element between the standards. The hole in the front standard 8 is threaded to receive the threaded extremity of the screw and enables the sharpening element to be secured in position on the device in a manner permitting rotational adjustment of the element as desired to compensate for wear of the cutting teeth thereon. It is also to be noted that the holes in the standards 8 and 8' are 50 located as to dispose the sharpening element at a slight angle to horizontal with the front end of the element at a slightly higher elevation than the rear thereof.

A pair of laterally spaced arms l carried by the base 6 and extending upwardly therefrom at opposite sides of the file element provide for mounting a pair of spherical blade retaining members it between them and the file element, and one at each side of the element. For this purpose the arms l5 are provided with socket like holes ll smaller than the balls 15 and in which the balls seat for universal motion relative to the arms. Inasmuch as the arms have a degree of resiliency, it will be seen that they hold the balls in firm but yielding engagement with substantially diametrically opposite side surfaces of the file element and thus retain the balls in their respective sockets.

In'using the embodiment of the knife sharpener described, the blade of the knife to be sharpened is inserted, cutting edge downward, between the teeth at one side of the file element and the adjacent blade retaining ball l6 as indicated in Figure 2. The blade is then drawn lengthwise rearwardly through the sharpener while a slight amount of downward pressure is applied to the blade to enable the ball !6 in coni tact therewith to yieldinglypress the inner side of the blade against the filing surface on the element '5. The sharpening stroke of the knife blade should be executed with the cutting edge of the knife as nearly horizontal as possible so that the teeth on the inclined file element areenabled to take progressively deeper cuts into the 4 edge portion of the blade as the same is drawn through the sharpener.

Such progressive cutting by the teeth on the file element is assured by mounting the element with its forward end at a slightly higher elevation than its rear end and by drawing the knife blade to be sharpened through the sharpener with the cutting edge of the blade in a substantially horizontal plane. In this manner maximum depth of the cut will be effected at the areas of the file element adjacent to the blade retaining balls l8, and minimum depth of cut will occur at the front raised end of the file element with. the cut increasing progressively in depth by the successive teeth rearwardly of the front of the file.

This results from the fact that the cutting edge of the blade when drawn through the sharpener in the manner described contacts the teeth at the front portion of the file element at points where the teeth are closer to the vertical plane containing the axis of the file element than the points of those teeth contacted by the cutting edge of the blade opposite the blade retaining ball l6. In other words, the points or cutting edges of the teeth in contact with the side of a knife blade at the cutting edge thereof define a gradually curving helix on the exterior of the file element.

It is important to note that the file element has a diameter substantially greater than the diameters of the blade retaining balls l5. This assures the sharpening of a keen hollow ground edge on the sharpener of this invention, as will be apparent from a consideration of the diagrams Figures 5a, 5b, and 50.

These diagrams depict successive stages in the sharpening of a blade edge drawn through the sharpener and it will be seen that the small diameter of the blade retaining ball l6 enables the knife blade B to be sharpened at both sides thereof beyond a plane DD intermediate and parallel to the sides of the blade and which plane intersects the curved surface of the file element as shown in Figure 511 at the time One side edge of the blade is fully sharpened.

Sharpening to this depth may be accomplished with a single stroke of the blade through the sharpener in the event the edge of the blade is not excessively dull, and thereafter the blade is transferred to the opposite side of the file element and drawn therethrough to produce hollow grinding or filing of the blade to a depth again beyond the median plane DD of the blade.

The grinding or filing of the opposite sides of the blade edge slightly beyond the central plane of the blade thus insures against the possibility of an incompletely sharpened edge remaining after the filing operation as so often happens with past types of knife sharpeners.

In the modified embodiment of the invention shown in Figure 4, sharpening of both sides of a knife blade edge is effected by means of a single sharpening stroke. This is accomplished by mounting two identical cylindrical file elements 1 in tandam, that is, with their axes parallel and spaced apart from one another a distance corresponding to the diameter of the file elements but one behind the other to provide concomitant sharpening of the sides of a knife blade drawn therebetween.

In this embodiment of the invention it will be seen that although two file elements are employed, only two spherical blade retaining elements IB'are required, one behind the foremost file elearcs, s61

ment 1 andv contacting the adjacent side; of the rearmost file element, and one ahead of therearmost file element and contacting the adjacent sideof the front file element. The arms. l5 which mount the balls are similar to those previously described but are: not opposite to one another, the: arms in this case being offset with relation to one another in the direction of the axes of the file elements.

In both of: the embodiments thus fardescribed, the base 6' is provided with an arcuate flange: 2d at its rear side behind the file element or elements, the opposite ends of the flange being bent in: wardly as at 2t to retain a strip of honing material 22 on the inner concave side of the flange. The honing material thus provides a convenient means for" removing from the edge of the: blade sharpened any slight burr which may have been raised by the file element and enables the knife edge to be honed to a razor-like edge.

In the Figures 6 to 9 embodiments of the. invention, the file element 1' is mounted. in a well or recess 25 opening to the rear face of a rectangular block-like support 26 for the element. The inner face of. an upright substantially fiat wall 21- at the: front of the block-like support defines the bottom of the recess 25, and the wall has a threaded hole. (not shown) therein to receive the screw H by which the file element is re-- tained' in place on the bottom wall 21-: within the recess 25.

Thescrew I i" mounts the file element 1 fixedly in place on the support 26 with the axis of the Intheseembodiments of the invention-the-blade retaining balls l'fi" are mounted in the mouths of holes 32 drilled endwise into the: opposite ends of the support 26 one common axis. spaced slightly above the axis of the mounting screw it" and substantially normal thereto. The mouths. of these holes, of course, open. into the recess 25 and compression springs 33 confined in the holes between the balls and set screws 34' closing. the outer ends of the holes firmly but yieldingly press the balls againstthe opposite cutting faces of. the file element at points slightly above the horizontal down from the top side thereof to provide a fiat substantially horizontal supporting surface 35 for the guide on a plane slightly beneath the upper surface of the file element and spaced a. distance beneath the top of the block-like support 26.

The guide 35 may comprise a substantially U- shaped. element, the legs so of. which laterally outwardly and upwardly toward thev ad jacent corners of the block-like supports and directly above the slots an. The upper endsnfrdefine restricted entrances to the knife blade slots.

A knife to be sharpened is inserted into one of the slots with its inner side edge engaged by l the adjacent extremity of the guide 35 and theresilience of the legs of the guide is such as to press the upper portions of the knife blade remote from. its cutting edge outwardly against the outer Wall of the slot 30, thereby holding the:

blade at the proper angle for sharpening.

The guide 35 is, of course, conveniently mounted onthe supporting surface 36 as by means of acap screw d5 threaded downwardly into thewall 21, and the guide is prevented from turning about the axis of the screw 45 by engagement of its rearward side edge with the front end of the fileelement, a portion of which projects to an elevation above the surface 36 as stated.

Although the file element l in the Figures 6 to 9 embodiments of the invention is set with its axis substantially horizontal, it will be seen that.

the arrangement of the sharpener is such that a knife may be drawn therethrough with its edge to be sharpened at a slight angle to the axis of the file element so that the progressive cutting action previously described will be achieved.

Cutting ridges or file teeth may be formed on the cylindrical blank for the file element in avariety of ways, as for example, by using a chisel toform a series of fine, closely spaced parallel file teeth of substantial arcuate length, It is only necessary, however, to form the fi-leteeth at two substantially diametrically opposite sur-;

faces of the file element, as shown best in Fig-- ures 6 and 8.

The element is provided with. a fiat'side 50-; is adapted to cooperate with. a pin 5| driven into the wall Hand projecting outwardly into the: recess beneath the flat to cooperate therewith preferably at the bottom thereof, which and. limit rotational adjustment of the file element. The: positioning of the pin 5i is such that rotational adjustment of the file element is limited to preclude adjustment thereof beyond thev of knives.

Asseen in Figures 7. and 8', it is extremly im-. portant: that the teeth of the file element be'ar-' ranged so as toslant upwardly and rearwardly along the surface of the element at both sides thereof, with their cutting edges facing forwardly When so toward the front of the sharpener. disposed, the file teeth slope rearwardly in the direction in which a knife blade is drawn through. the sharpener to assure a true cutting action as: distinguished from the scraping action inherent" in most previous types of knife sharpeners.

Moreover, the file teeth in this disposition of the same cut upwardly along the adjacent side of" the knife blade away from the extreme cutting" edge of the blade to force chips or shavings upwardly away from the point or points of contact I between the file teeth and knife blade. thus. precluding cloggingof the file element and assuring. the: cutting or filing of a smooth. edge on the,

blade entirely without burr or wire edge.

From the foregoing. description. taken together with the accompanying drawings, it will be ap'x; 1 parent that this invention provides a sharpener;

I; for knives and other edged tools which enables hollow grinding or sharpening of the tools with substantially no burr or wire edge on the blade, and which is particularly convenient to use.

What I claim as my invention is:

1. A knife sharpener comprising: a substantially cylindrical, file-like sharpening element; a base; a pair of spaced apart parallel standards extending upwardly from said base; a screw received in holes in said. standards and in an axial hole in said sharpening element to mount the sharpening element lengthwise between the standards and with its axis spaced above the base, said screw being threaded into one of said standards to enable the sharpening element to be clamped in any one of a number of positions of rotational adjustment on said standards; an arm extending upwardly from the base on either side of the sharpening element; and a spherical blade guide member received in a socket-like hole in each of said arms and biased by said arms toward engagement with diametrically opposite side surfaces of the sharpening element.

2. A knife sharpener comprising: a sharpening element having cylindrical surfaces at substantially diametrically opposite side surfaces thereof; closely spaced relatively fine undercut file .teeth on said surfaces; a support for said element; means mounting said sharpening element on the support for rotational adjustment about an axis common to said cylindrical surfaces of the element with the cutting edges of the file teeth disposed at a substantial angle to the line along which the edge of a knife blade is adapted to travel during sharpening thereof; a pair of blade guide elements having convex surfaces; and means on said support mounting each of said guide elements alongside one of said surfaces on the element in engagement with the teeth thereof at a point on a line above the axis of the file element and for yieldingly biasing the guide elements toward engagement with the file teeth on said surfaces so that the guide elements'retain one side of the cutting edge of a knife blade interposed between them and the sharpening element in cutting engagement with the file teeth.

3. A knife sharpener comprising: a support; a pair of substantially cylindrical sharpening elements each having closely spaced file teeth on their peripheries; means on the support mounting said sharpening elements in end to end relationship with their axes ofiset laterally a distancesuch that the cutting edges of teeth on adjacent sides of the elements are substantially tangent to a common plane passing between the sharpening elements, and whereby the edge of a knife blade inserted and drawn lengthwise be-- tween the two elements in said plane will be sharpened simultaneously at both sides of the blade; and blade guide means cooperating with the adjacent sides of the sharpening elements and with each other to hold the blade of a knife inserted between the sharpening elements at the proper angle of presentation to the file teeth on the sharpening elements.

4. A knife sharpener of the character described comprising: a substantially upright supporting iii) member having a recess opening to its back side;

along, said supporting member having spaced slots therein leading downwardly from the top of the member in line with said cylindrical filing surfaces of the file element to enable the blade of a knife to be inserted into th sharpener for presentation of one side of the cutting edge of the blade to one of said cylindrical filing surfaces on the file elements; a guide member carried by.

firm but yielding engagement with the filing surfaces adjacent thereto so that said guide members define the extent to which a knife blade may be inserted into said slots for presentation to the file element.

5. A knife sharpening device of the character described comprising: a supporting member including a substantially upright wall having a recess opening to the rear face thereof; a file element mounted on said upright wall in said recess, said file element having cylindrical filing surfaces on its opposite sides extending rear-.

wardly from said wall and each substantially tangent to a vertical plane normal to said faceof the upright wall upon which the file element is mounted; said supporting member having substantially narrow slots therein in line with said filing surfaces and opening to the top of the supporting member to enable a knife blade to be inserted into the device, cutting edge downward, for presentation of one side of its cutting edge to one or the other of said filing surfaces on the file element; and means carried by the supporting member and yieldingly engaging the opposite filing surfaces of the file element at points intermediate the ends of the file element for limiting downward insertion of a knife blade into said slots and to hold the blade with the median plane thereof at an angle intersecting the adjacent filing surface on the element regardless of the degree of tilt of said blade within limits afforded by said slots, said means translatingdownward pressure on the knife blade into a lateral force urging the blade against the filing surface presented thereto.

6. A knife sharpener device of the character described comprising: a supporting member in. cluding a substantially upright wall having a recess opening to the rear face thereof; a screw having its extremity threaded into the bottom of said recess in the upright wall and extending substantially horizontally and centrally in said recess; a file element mounted on the shank of the screw for rotation thereon between a number of predetermined positions at each of which the element may be readily fixed with relation to the supporting member by turning the screw to clamp the element between the head of the screw and the bottom of said recess; substantially diametrically opposite cylindrical side surfaces on said file element extending rearwardly from the bottom of said recess and having file teeth thereon the cutting edges of which are tangent to vertical planes normal to said surface of the upright wall upon which the file element is mounted; said supporting member having a, pair of substantially narrow slots leading downwardly from the top thereof and each aligning with one of said filing surfaces on the file element to enable a knife blade to be inserted into the device cutting edge downward for presentation of one side of its cutting edge to one or the other of said filing surfaces on the file element; means for limiting insertion of a knife blade into the slots including a pair of balls each received in an aperture in the supporting member opening into said recess alongside one of the filing surfaces on the file element, and means for firmly but yieldingly urging said balls into engagement with said filing surfaces; and cooperating stop means on the file element and the supporting member for precluding rotational adjustment of the file element beyond the limits of the filing surfaces thereon so as to assure the presentation of file teeth to a knife blade inserted in one or the other said slots of the device despite the angular position of the file element on its screw.

'7. In a knife sharpener: a support including an upright member; a file element mounted on said upright member, said file element having opposite substantially cylindrical side surfaces extending rearwardly from said member and provided with circumferential file teeth of substantial length; and a pair of knife blade guides carried by said support, each comprising a ball rotatably mounted on the support and in contact with the file teeth on one of said surfaces intermediate the ends of the teeth and intermediate the ends of said surface, each of said guides being adapted to retain one side of a knife blade inserted between it and the toothed surface of the element adjacent thereto in cutting engagement with the file teeth on said surface.

8. In a knife sharpener: a support including an upright member; a file element mounted on said upright member, said file element having opposite substantially cylindrical side surfaces extending rearwardly from said member; and substantially circumferentially extending parallel file teeth on said surfaces, said file teeth having substantial length and having their cutting edges facing said member, each of said toothed surfaces being adapted to be engaged by one side of a knife blade to effect hollow grinding of the blade upon drawing of the blade rearwardly along the file element with its cutting edge facing downwardly and in contact with one of said toothed surfaces, all of the file teeth on each of said surfaces being disposed at on a substantial upward and rearward slant away from said upright member to force chips upwardly away from the point of contact between the knife blade and the file teeth.

9. As an article of manufacture, a grinding element suitable for use in knife sharpening devices, comprising a member having opposite cylindrical surfaces thereon each provided with closely spaced sharp edged substantially circumferential edges defining file teeth of substantial length, the

' teeth on one surface having a right helical arrangement, and the teeth on the opposite surface having a left helical arrangement, and all of said teeth having their cutting edges facing in the same direction.

10. The article of manufacture set forth in claim 9 further characterized by the fact that all of said file teeth are undercut.

11. In a knife sharpener: a support; a cylindrical file element mounted on said support with its axis substantially horizontal, said file element being provided with circumferential file teeth of substantial length along its opposite side surfaces; a pair of guide elements having convex surfaces; means mounting one of said guide elements on said support at each side of said file element, with the convex surfaces of said guide elements tangent to the side surfaces of said file element on a line spaced above the axis of the file element; and means on said support defining spaced apart stops adapted to be engaged by the sides of a knife blade having its edge inserted between the convex surface of each guide and the adjacent cylindrical surface of the file element to limit tilting of the knife blade to a degree such that its median plane, when extended, will always pass between the axis of the file element and the point of tangency of the adjacent guide element.

12. In a knife sharpener: a support; a substantially cylindrical file element mounted on said support with its axis substantially horizontal,

said file element being provided with circumferential teeth of substantial length along its opposite side surfaces; a pair of guide elements having convex surfaces; means mounting one of said guide elements on said support at each side of said file element, with the convex surfaces of said guide elements contiguous to the teeth on the side surfaces of said file element; and a shoulder on said support, above each of said guide elements, said shoulder being adapted to be engaged by the surface of a knife blade having its cutting edge inserted between the convex surface of one of the guide elements and the adjacent cylindrical surface of the file element to preclude tilting of said blade in a direction such that its median plane, when extended, passes through said convex surface and constraining said blade to an attitude such that said plane passes between the axis of the file element and the exterior surface thereof alongside the blade, closely adjacent to said exterior surface.

13. In a knife sharpener: a supporting member; a sharpening element mounted on said supporting element and having opposite side surfaces which are segments of a cylinder; oppositely pitched helical file teeth on said side surfaces, said teeth having substantial length and all having their cutting edges facing in the same direction; and guide members on said supporting element adjacent to each of said side surfaces and positioned to be engaged by the blade of a knife, the cutting edge of which is presented lengthwise to one of said toothed side surfaces for sharpening, to constrain the blade to an attitude such that the median planethereof, extended, will always pass chordally through the adjacent cylindrical surface of the element near the exterior thereof.

ALFRED E. ANHEUSER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 668,226 Shoemaker Feb. 19, 1901 1,938,928 Papsons Dec. 12, 1933 1,968,472 White July 31, 1934 2,404,025 Barnes July 16, 1946 FOREIGN PATENTS Number Country Date 155,914 Great Britain Dec. 29, 1920 

